Ultra short wave communication system



Jan. 28, 1936.

C. W. HANSELL ULTRA SHORT WAVE COMMUNICATION SYSTEM Filed June 2, 1933.2 Sheets-Sheet 1 u E 5 M Y f WH E mw. m EEQ/ o VC n www A R A L C Y B 2Sheets-Sheet 2 28, 1936. Q w HANSELL ULTRA SHORT WAVE COMMUNICATIONSYSTEM Filed June 2, 1953 Patented Jan. 28, 1936 ,e UNITED STATES PATENToFFlcE ULTRA SHORT WAVE COMIWUNICATION SYSTEM Clarence W: Hansell, PortJefferson,

N. Y., as-

signor to Radio Corporation of America, a corporation of DelawareApplication June 2, 1933, Serial No. 673,974

, wavesb-y means'`V of a common oscillator and reector system.

A feature of the present invention is the reflecting system utilizedwhich comprises two re-V flectors, one of a parabolic type and the othera 15. hemi-spherical rellector located in the focus of the; parabolicreflector and arranged4 to direct energy into said parabolic reflector.These reectors are arranged upon a pivoted support by means of whichtransmission and reception may. be carried out any desired direction.

A further feature is the means employed to prevent interaction betweenthe transmitting and receiving circuits of the system.'

In brief, the invention comprises an ultra high frequency oscillator,lfor example, a Barkhausen oscillation, the radiating elements ofV whichare located at the center of a hemi-spherical reector and in the focusof and facing towards a parabolic reflector. This oscillator is arrangedto produce radiation and, in practice, will ordinarily utilize theenergyA feed lines as the oscillatory circuit on which standing wavesare allowed to develop. For transmission purposes, the hemisphericalreector catches all the radiation going r out in a more or less forwarddirection and sends it back towards the center of the oscillator systemso that it will fall upon the parabolic Vreilector as` if it had comedirectly from the oscillator. By properly dimensioning the two reiectors, all of the radiation is caught by the reflector system andreflected from the parabolic reflector in the desired direction. Thusthere is no-leakage of energy due to radiation missing the reector andmaximum directivity is obtained. 1t is proposed to modulate the outputof the oscillator by varying the potential on its electrodes: in anysuitable manner. The same` system may also be used for reception bycausing any energy falling upon the rei:l flector tol be impressed` uponthe oscillator circuits and thus give rise to a variation in the inputelectrode currents to the oscillator,

A more complete understanding of the invention may be had by referringto the following 55. detaileddescription which is accompanied by 10claims. (c1. 25u-e) drawings, wherein Figure 1 illustrates a completeultra short wave communication system for effecting simultaneoustransmission and receptionat a single point in accordance with theprinciples of the present invention, and Figure 2 illustrates amodification thereof wherein there is utilized a Wheatstone bridge orhybrid coil arrangement for aiding in preventing interaction between thetransmitter and receiver of the reflector system.

Referring to Figure 1 in more detail, there is shown, schematically, aBarkhausen oscillator l, the eiective radiating center of which islocated at the center of a heini-spherical reflector 2 and in the focusof a parabolic reflector 3, both being pivotally mounted at 2li and 2|for movement in any desired direction. Hemi-spherical reflector 2 isarranged to direct energy received by it back toward the parabolicreflector 3 fromwhich radiation is reflected in the desired direction. Asource of potential 4 is provided for supplying a relatively highpositive potential to the grid of the Barkhausen oscillator, and asource of potential 5 acts to supply a small negative potential to theanode thereof. This anode may be eitheriat a negative potential, asshown, or else at a small positive or even at the same potential as thecathode. For tuning the tube leads., there is provided a group of bypasscondensers 6 in which adjustable taps on each of the tube leads serve tojoin all the leads together for radio frequency currents, and stillleave each lead of correct length for optimum oscillating conditions.The oscillations generated in the Barkhausen oscillator l are caused toexist as standing waves on portions of the leads extending from theelectrodes of the oscillator l through the parabolic reector 3 to thesources o-f potential 4 and 5.

For modulating the oscillations, there is provided any suitable signalmodulating means, such as a microphone 1, which is coupled to audiofrequency transformer l0 through an amplier 8 over any suitabletransmission line, such as a telephone line 9, the currents in thesecondary of transformer I0 being arranged to vary the grid potential onthe Barkhausen oscillator and thus also vary the strength of theoscillations, The variations in strength of the oscillations will bedetected at a distant receiving station. If desired, both the grid andanodel potentials may be modulated in order to obtain amplitudemodulation independent of frequency modulation or, in some cases,frequency modulation independent of amplitude modulation. One such U. S.Patent 1,938,749, granted December 12, 1933, to N. E. Lindenblad.

The system indicated may also be used for reception since any energyfalling upon the parabolic reflector 3 and being impressed upon theoscillator circuits will give rise to a variation in input current tothe oscillator by adding to and opposing the local oscillations. If thetransmitter from which it is desired to receive a communication has itsfrequency made somewhat different than the oscillator shown in thedrawings, then the electrode input current will vary periodically at arate corresponding to the difference between the two frequencies andthese variations will have an amplitude substantially proportional tothe strength of the received radiation. Preferably, the beat between thecarrier of the transmitter to be received and that of the oscillatorshown in the gure should be at some frequency higher than audibility. Itmight, for example, be 1,000,000 cycles per second. By means of a tunedcircuit I I inserted in series with the lead to the grid there can beselected this one million cycle beat, and the energy from this circuitmay be coupled through an intermediate frequency receiver I3 to anordinary loudspeaker or telephone receiver IZ for enabling the receptionof the modulation of the distant transmitter. The system may be employedfor receiving communications from any one of a number of distanttransmitters operating near the same frequency by simply tuning theintermediate frequency receiver for the beat frequency between thedistant transmitter and the local ultra short wave oscillator. Ofcourse, if the distant transmitters are located in different directionsthe reflector must be turned on its pivot to selectively receive fromthe desired direction.

In the circuit shown, the intermediate frequency tuned circuit I I hasnegligible impedance for the audio input energy transmitted over line Sand transformer I0, and. permits the modulation of the oscillator due tothis audio energy without any impediment. Audio transformer I0 isdesigned to present a low impedance to the 1,000,000 cycle beatfrequency, and the secondary winding thereof may, if desired, be shuntedby a bypass condenser I5 which has relatively low reactance for theintermediate frequency. In the arrangement indicated it is possible thatmodulation of the oscillator for transmission purposes may cause somevariation in the strength of the intermediate frequency impressed uponthe intermediate frequency receiver I3, though, in general, there is atendency for the intermediate frequency energy to be independent of thestrength of the local oscillations over a considerable range. In anycase its only effect is to make a speakers voice audible in his ownreceiver and this is not objectionable since it is the common conditionin almost all telephone circuits.

If it is desired to prevent the audio input energy impressed by amplierS upon line 9 and transformer I0 from being reproduced through theintermediate frequency receiver I3, an arrangement such as is indicatedin Figure 2 may be employed wherein a hybrid coil is used. This hybridcoil is in the nature of a Wheatstone bridge which permits combiningoutgoing and incoming energies into a single circuit without permittingthe outgoing energy to return again to the transmitter via the receiverin a manner to set up spurious oscillations or singing.

In Figure 2 microphone 1 is shown connected in parallel with a telephonereceiver I2 across the common telephone transmission line 9 which, inturn, is connected to the ends of two windings IS and. I1 of a hybridcoil 23. The opposite ends of the windings are connected to an impedanceZ which simulates or matches the electrical constants of the telephoneline. From the center of windings I6 and I1 connections are made to theinput terminals of the transmitter amplier 8. A second winding or pairof windings I8 and IS on the hybrid'coil are connected to the output ofthe intermediate frequency receiver I3.

With the arrangement shown in Figure 2, when l the adjustments arecorrect, output energy from the receiver cannot enter the'transmitter,but half of the energy is transmitted over the wire line 9 to theoperators receiver i2. The telephone transmitter currents are likewiseprevented by the hybrid. coil 23 from entering the receiver outputcircuit, but this is not important inasmuch as the receiver is aunilateral device and cannot cause singing due to reversed energytransmission through it.

'Ihe foregoing invention is arranged to provide a highly efficientcommunication system Vat extremely low wave lengths of less than onemeter with excellent power output and may be used for such purposes ascommunication between ships in a harbor, between ships of a fleet, forrelatively short distance communication between individuals, betweenbuildings, across streams, etc.; in fact, the invention may be usedwherever the relative cheapness of a single system would be an advantagefor both transmission and reception.

I claim:

1. An ultra short Wave communication system for the simultaneoustransmission and reception of electromagnetic energy comprising a wavereflecting surface formed to approximate a paraboloid and ahemi-spherical reflector mounted in the focus of said reflecting surfaceand arranged to direct energy toward said surface, a Barkhausenoscillator comprising a cathode, anode and control, electrode mounted inthe center of said hemispherical reflector, said control electrode beingat a high positive potential with respect to said lanode and cathode,sources of potential for said electrodes, energy feed leads extendingfrom said oscillator through said reflecting surface to said sources,signal modulating means coupled to the electrodes of said oscillator,and receiving apparatus also coupled to said electrodes.

2. An ultra short Wave communication system for the simultaneoustransmission and reception of electromagnetic energy comprising aparabolic reflector and a heini-spherical reector mounted in the focusof said parabolic reflector and arranged to direct energy toward saidparabolic reflector, a Barkhausen oscillator comprising a cathode,anode, and control electrode mounted in the center of saidheini-spherical reector, said control electrode being at a high positivepotential with respect to said anode and cathode, sources of potentialfor said electrodes, energy feed leads extending from said oscillatorthrough said parabolic reector to said sources, signal modulating meanscoupled to the electrodes of said oscillator, receiving apparatus alsocoupled to said electrodes, and a Wheatstone bridge arrangement coupledto said energy feed leads for preventing undesirable reaction betweensaid transmitter and receiver.

3. An ultra short wave communication system for the simultaneoustransmission and reception of electromagnetic energy comprising aparabolic reflector and a hemi-spherical reflector mounted in the focusof said parabolic reflector and arranged to direct energy toward saidparabolic reflector, an oscillator comprising a cathode, anode, andcontrol electrode mounted in the center of said hemi-sphericalreflector, said control electrode being at a high positive potentialwith respect to said anode and cathode, sources of potential for saidelectrodes, energy feed leads extending from said oscillator throughsaid parabolic reflector to said sources, signal modulating meanscoupled to lthe electrodes of said oscillator, a parallel tuned circuittuned to an intermediate frequency coupled to said oscillator, anintermediate frequency receiver connected to said parallel tunedcircuit, an acoustic device, said intermediate frequency receiver beingarranged to supply audio frequencies to said acoustic device. l

4. An ultra short wave communication system for the simultaneoustransmission and reception of. electromagnetic energy comprising aparabolic reflector and a hemi-spherical reflector mounted in the focusof said parabolic reflector and arranged to direct energy toward saidparabolic reilector, a Barkhausen oscillator comprising a cathode,anode, and control electrode mounted in the center of saidhenri-spherical reflector, said control electrode being at a highpositive potential with respect to said anode and cathode, sources ofpotential for said electrodes, energy feed leads extending from saidoscillator in a direction along Vthe `focal line of said parabolicreflector to said sources, signal modulating means coupled to theelectrodes of said oscillator, and

receiving apparatus also coupled to` said electrodes.

5. An ultra short wave radio communication system for the simultaneoustransmission and reception of Waves below one meter comprising a singleoscillator for both transmission and reception, a reflector, saidoscillator being at the focus of said reflector, and feed leads havingstanding waves thereon extending along the focal line of said reflectorfrom the electrodes of said oscillator to energy supplymeans.

6. An ultra short wave radio Vcommunication system for the simultaneoustransmission and .reception of waves below one meter having, in

combination, a parabolic reflector arrangement pivoted so as to becapable of `motion for directive action in any desired direction, and anoscillatory system extending along the focal line of said parabolicreflector comprising an electron discharge device oscillator and leadsfrom said oscillator through said reflector, and means for producingstanding waves on said leads.

7. An ultra short wave radio communication system for the simultaneoustransmission and reception of waves below one meter having, incombination, a parabolic reflector and a hemi-spheriarranged to' directenergy toward said parabolic reflector, and an oscillatory system whoseeffective center is at the focus of both of said reflectors, saidoscillatory system comprising a single electron discharge device havingan anode, cathode, and control electrode, leads for said electrodesextending through said parabolic reflector to energy supply means formaintaining said control electrode at a positive potential relative tothe cathode and anode, and signal modulating means in circuit with saidelectrodes whereby there are Vcaused to exist standing waves on saidleads, said reflectors being pivotally mounted for directive action onthe arc of a circle.

9.'An ultra short wave radio communication system for the simultaneoustransmission and reception of waves having, in combination, a parabolicreflector and a heini-spherical reflector arranged to direct energytoward said parabolic reflector, and an oscillatory system whoseeffective center is at the focus of both of said reflectors and whichextends along the focal line of said reflectors at least up to saidparabolic reilector, a transmitter and a receiver in circuit with saidoscillatory system, said receiver having means for selectively receivingthe beat frequency between the oscillations generated by saidoscillatory system and the received waves, and a balancing circuitV forpreventing undesirable reaction between the transmitted and receivedmodulation currents.

10. An ultra short wave communication system for the transmission andreception of electromagnetic energy below one meter comprising aparabolic reflector and a hemi-spherical reflector mounted in the focusof said parabolic reflector and arranged to direct energy towards saidparabolic reflector, a radiating system at the focus of both saidreflectors comprising a multi-electrode electron discharge deviceoscillator whose control electrode is at a high positive potentialrelative to its cathode, and feed leads having standing waves thereonextending from the electrodes of said device along the focal line ofsaid reflector through said parabolic reflector to energy supply means,signal modulating means coupled to the electrodes of said oscillator andreceiving apparatus also coupled toy said electrodes.

. CLARENCE W. HANSELL.

